WO2025016903A1

WO2025016903A1 - Recovery of polyesterols from polyesterol-based polyurethanes via hydrolysis and re-condensation

Info

Publication number: WO2025016903A1
Application number: PCT/EP2024/069817
Authority: WO
Inventors: Andreas Thomas HAEDLER; Patrick SCHMATZ-ENGERT; Matthias Hinrichs; Marta KUBIAK; Torsten Mattke; Markus Schuette
Original assignee: Basf Se
Priority date: 2023-07-14
Filing date: 2024-07-12
Publication date: 2025-01-23

Abstract

The present invention relates to a process for recycling of polyurethane or polyisocyanurate containing waste comprising the steps of providing a composition (M1) comprising a comminuted polyurethane or polyisocyanurate material which is obtained from at least one polyesterpolyol (P1), depolymerization of the comminuted polyurethane or polyisocyanurate; separation of the amine component derived from depolymerization and the polyol components or polyol fragments obtained, in an amine rich phase as mixture (MA) and an amine poor phase as mixture (MP); treatment of the amine poor phase to adjust the ratio of acids and polyalcohols in mixture (MP) to obtain mixture (MP'); and treatment of mixture (MP') to achieve condensation of polyalcohols and acids in the mixture. The present invention also relates to a process for preparing a polyester polyol, a polyol composition obtained or obtainable according to the process according to the invention and the use of the polyol composition for the preparation of polyurethanes or polyisocyanurates.

Description

Recovery of polyesterols from polyesterol-based polyurethanes via hydrolysis and re-condensa- tion

The present invention relates to a process for recycling of polyurethane or polyisocyanurate containing waste comprising the steps of providing a composition (M 1) comprising a comminuted polyurethane or polyisocyanurate material which is obtained from at least one polyesterpolyol (P1 ), depolymerization of the comminuted polyurethane or polyisocyanurate; separation of the amine component derived from depolymerization and the polyol components or polyol fragments obtained, in an amine rich phase as mixture (MA) and an amine poor phase as mixture (MP); treatment of the amine poor phase to adjust the ratio of acids and polyalcohols in mixture (MP) to obtain mixture (MP’); and treatment of mixture (MP’) to achieve condensation of polyalcohols and acids in the mixture. The present invention also relates to a process for preparing a polyester polyol, a polyol composition obtained or obtainable according to the process according to the invention and the use of the polyol composition for the preparation of polyurethanes or polyisocyanurates.

Products containing polyurethane materials are widely used in industry and in everyday applications. Because of the tremendous and still increasing prevalence of polyurethane materials, there is a large amount of waste of polyurethane materials (e.g., from old mattresses or seating furniture, car seats, refrigerators or insulation boards). This waste of polyurethane materials should be used appropriately and as ecologically friendly as possible. One way of such use of polyurethane materials is the recovery of raw materials from the polyurethane materials. Apart from so-called mechanical recycling methods, which teach a physical comminution, chemical recycling processes are known.

Remonomerization strategies discussed in the literature and patents include hydrolysis, alcoholysis, in particular glycolysis, aminolysis and acidolysis. For example WO 2021/023889 A1 discloses a method for alcoholizing and hydrolyzing polyurethane materials.

In general, hydrolysis techniques lead to a CO2 release, which dissolves in water as carbonic acid under pressure and leads to a deactivation of the mostly basic catalysts. Especially in the literature, frequently used inorganic strong bases, such as sodium hydroxide or potassium hydroxide irreversibly deactivate. Further catalysts are for example mentioned in WO 2022/171586 and US 2022/0251328 In addition, salts are often formed, which represent a challenge in the process engineering process. Another aspect is the splitting of polyester polyols. These consist mainly of dicarboxylic acids and diols, e.g. glycols and butandiol. The ester bonds are not stable in a hydrolytic remonomerization strategy and there is a cleavage of the polyester polyols into polyester polyol oligomers and/or their monomeric building blocks. The released acids react with the bases used as catalysts and with the released amine (the isocyanate corresponding amine), which can lead to a reduction in the yield of valuable products. For further processing only some of the side products formed can be converted back into the corresponding acids and amines, which is associated with a further process engineering effort. In many chemical recycling processes of polyurethanes based on polyesterols, the integrity of the later is damaged. Separation and purification of the respective monomers i.e. alcohols and acids of the polyesterols is time and energy consuming.

In view of the above, it is an object of the present invention to provide a process to recover polyesterols from polyurethane materials which is as simple as possible, and which allows to recover raw materials having good quality.

The problem is solved according to the present invention by a process for recycling of polyurethane or polyisocyanurate containing waste comprising the steps of a) providing a composition (M1) comprising a comminuted polyurethane or polyisocyanurate material which is obtained from at least one polyesterpolyol (P1) , b) depolymerization of the comminuted polyurethane or polyisocyanurate provided in step a) c) separation of the polyol components or polyol fragments from the amine component derived from depolymerization obtained in step c), in an amine rich phase as mixture (MA) and an amine poor phase as mixture (MP); d) treatment of the amine poor phase to adjust the ratio of acids and polyalcohols in mixture (MP) to obtain mixture (MP’); e) treatment of mixture (MP’) to achieve condensation of polyalcohols and acids in the mixture.

The process according to the present invention comprises steps a), b), c), d)and e) but may comprise further steps. It has been found that the specific sequence of process steps according to the present invention allow to recover polyesterpolyols from polyurethane or polyisocyanurate materials in high quality in a simple manner.

It has surprisingly been found that in the process, the polyols or polyol fragments remain in an amine poor phase and the polyesterpolyols can be easily recovered by re-condensation.

It has been found that the process is particularly suitable for the recycling and remonomeriza- tion of polyurethane foams. Thus, according to the present invention, the polyurethane or polyisocyanurate material preferably is a polyurethane or polyisocyanurate foam.

In the context of the present invention, the term polyol denotes a compound having two or more OH groups, for example those with functionality from 2 to 8. The term polyols encompasses compounds with different chemical structure, for example polyether polyols, polyester polyols, and mixtures thereof. According to the present invention, the polyurethane or polyisocyanurate material is obtained from at least one polyesterpolyol (P1). Further polyols such as further polyester polyols or polyether polyols may be used for the preparation of the polyurethane or polyisocyanurate material. Thus, depending on the depolymerization step b), typically a mixture of polyols and polyol fragments is obtained which typically comprises at least fragments and/or monomers of polyester polyol (P1 ) and may comprise further polyols or polyol fragments.

According to step a), a composition (M1 ) comprising a comminuted polyurethane or polyisocyanurate material which is obtained from at least one polyesterpolyol (P1), is provided.

In the context of the present invention, a “comminuted polyurethane or polyisocyanurate material” means the material is obtained from a compact material or a foam and the comminuted polyurethane or polyisocyanurate is for example used in shredded form, in the form of granules, flakes, as an agglomerate, or as a powder. The polyurethane or polyisocyanurate materials can be comminuted by conventional methods, for example by shredding, e.g. in a rotation mill or rotary mill at room temperature or with cooling, to a particle size of ordinarily less than 500 mm, for example to a particle size in the range of from 10 to 500 mm, preferably to a particle size of less than 20 mm, or ground, e.g. by known cold grinding processes. Preferably, for a milled foam a particle size of less than 5 mm is selected, for example a particle size in the range of 0.01 mm to 5 mm, and preferably in the range of 0.01 mm to 1 mm.

The properties of the polyurethane or polyisocyanurate materials might vary in broad ranges. Preferably, polyurethane or polyisocyanurate materials, in particular polyurethane foams are used in the process of the present invention. According to a further embodiment, the present invention is also directed to the process as disclosed above, wherein the polyurethane materials are selected from the group consisting of polyisocyanate derived polyurethane foams.

The polyurethane or polyisocyanurate materials, in particular the foams used in the present invention are preferably obtained from items produced from polyurethane or polyisocynurate materials, in particular foams at a time after use for the purpose for which they were manufactured or polyurethane waste from production processes. Before subjecting to the process of the present invention, the items may be subjected to sorting steps and/or to mechanical comminution. That is, further sorting and bringing the items into appropriate sizes, e.g., by shredding, sieving or separation by rates of density, i.e. by air, a liquid or magnetically. Optionally, these fragments may then undergo processes to eliminate impurities, e.g. paper labels. Furthermore, steps to remove blowing agents may be included in the process. Suitable methods are in principle known to the person skilled in the art.

Herein, the term “polyurethane waste”, “polyurethane foam waste” includes end-of-life polyurethane, in particular foams and production rejects of PU foams or waste generated through further processing of PU, in particular foams. In this context, the term “spent polyurethane” or “ spent polyurethane foam” denotes an item produced from a polyurethane, in particular a foam at a time when it has already been used for the purpose for which it was manufactured. “Production rejects of polyurethane foams" denotes polyurethane foam waste occurring in production processes of PU foams.

Generally, polyurethanes are produced by a reaction between a polyisocyanate component and a polyol component. Typically, further materials, in particular additives, such as flame retardants (e.g. phosphorous-based), polymerization catalysts (e.g. tertiary amines), fillers and surfactants as siloxanes can be added in the production process of the polymers.

The properties of a polyurethane, in particular a polyurethane foam are influenced by the chemistry of polyisocyanate and polyol components used and the recipe applied in polymerization. For example, the starting materials may influence the crosslinking density of the polymers in a three-dimensional network. Rigid polyurethane foams are typically obtained from monomers with a comparably low molecular weight and high functionality creating a highly crosslinked, dense network.

Industrially and consequently in large quantities, especially methylenedi(phenylisocyanate) (MDI) or its polymeric forms or tolylene 2,4 and 2,6-diisocyanate (TDI) are used as polyisocyanate components for the production of PU rigid foams and PU flexible foams. For a representative composition of these PU foams, see for example US 9,023,907 B2, WO 2015/121057 and WO 2013/139781.

Organic polyisocyanates that can be used in the preparation of polyurethanes are any of the known organic polyisocyanates, preferably aromatic polyfunctional isocyanates. In the context of the present invention, the term polyisocyanate encompasses isocyanates with 2 or more isocyanate groups, i.e. also diisocyanates.

Suitable polyisocyanate components used for the production of the polyurethanes or polyisocy- anurates comprise any of the polyisocyanates known for the production of polyurethanes or pol- yisocyanurates. These comprise the aliphatic, cycloaliphatic, and aromatic difunctional or polyfunctional isocyanates known from the prior art, and also any desired mixtures thereof. Examples are diphenylmethane 2, 2’-, 2,4’-, and 4,4’-diisocyanate, the mixtures of monomeric diphenylmethane diisocyanates with diphenylmethane diisocyanate homologs having a larger number of rings (polymer MDI), isophorone diisocyanate (IPDI) and its oligomers, toluene 2,4- and 2,6- diisocyanate (TDI), and mixtures of these, tetramethylene diisocyanate and its oligomers, hexamethylene diisocyanate (HDI) and its oligomers, naphthylene diisocyanate (NDI), and mixtures thereof.

Preferably, toluene 2,4- and/or 2,6-diisocyanate (TDI) or a mixture thereof, monomeric diphenylmethane diisocyanates, and/or diphenylmethane diisocyanate homologs having a larger number of rings (polymer MDI), and mixtures of these are used. Other possible isocyanates are mentioned by way of example in "Kunststoffhandbuch [Plastics handbook], volume 7, Polyurethane [Polyurethanes]", Carl Hanser Verlag, 3rd edition 1993, chapter 3.2 and 3.3.2. The organic and polyisocyanates may be used individually or in the form of mixtures.

According to the present invention, the polyurethane or polyisocyanurate material which is obtained from at least one polyesterpolyol (P1). In the context of the present invention, also mixtures of polyesterpolyols or mixtures comprising further polyols may be used. Further polyols are for example polyetherpolycarbonates, polyetheresterpolyols and polyetherpolyols. Preferably, only polyesterpolyols are used for the preparation of the polyurethane or polyisocyanurate material.

The polyurethane or polyisocyanurate material may for example be based on tolylene 2,4- and/or 2,6-diisocynate (TDI) and a polyol composition comprising at least one polyesterpolyol (P1) or on monomeric diphenylmethane diisocyanates (MDI) and a polyol composition comprising at least one polyesterpolyol (P1) or diphenylmethane diisocyanate homologs having a larger number of rings (polymer MDI) and a polyol composition comprising at least one polyesterpolyol (P1) or on hexamethylene diisocyanate (HDI) and a polyol composition comprising at least one polyesterpolyol (P1) or on naphthylene diisocyanate (NDI) and a polyol composition comprising at least one polyesterpolyol (P1).

Polyesterols are by way of example produced from aliphatic or aromatic dicarboxylic acids and polyhydric alcohols, polythioether polyols, polyesteramides, hydroxylated polyacetals, and/or hydroxylated aliphatic polycarbonates, preferably in the presence of an esterification catalyst. Other possible polyols are mentioned by way of example in "Kunststoffhandbuch [Plastics handbook], volume 7, Polyurethane [Polyurethanes]", Carl Hanser Verlag, 3rd edition 1993, chapter 3.1.

Polyesterpolyol (P1) may for example be selected from polyester alcohols whose OH numbers are in the range from 25 to 800 mg KOH/mg, in particular from 30 to 500 KOH/mg. According to the present invention, preferably a polyol component having a functionality of from 1 to 6, preferably between 1 to 4.5 is used, in particular in the range of from 1 to 4.1 , more preferable in the range of from 1 to 3.9, most preferable in the range of from 1 .1 to 3.5. It is also possible here to use mixtures of polyols. If polyols having a higher functionality are used in these polyol mixtures, the functionality of the mixture preferably is in the range of from 1 to 4.5

The polyester alcohols used are mostly prepared via condensation of polyhydric alcohols, preferably polyetherpolyols with a molecular weight up to 800 g/mol, preferably up to 650 g/mol, or diols, having from 2 to 12 carbon atoms, preferably from 2 to 6 carbon atoms, with polybasic carboxylic acids having from 2 to 12 carbon atoms, e.g. succinic acid, glutaric acid, adipic acid, suberic acid, azelaic acid, sebacic acid, decanedicarboxylic acid, maleic acid, fumaric acid, or preferably phthalic acid, isophthalic acid, terephthalic acid, or the isomeric naphthalenedicarboxylic acids. Also cyclic anhydrides may be used such as for example phthalic acid dianhydride. Suitable further polyols which may be used are in principle known to the person skilled in the art. Suitable are for example polyetherols. Suitable polyetherols are by way of example produced from epoxides, for example propylene oxide and/or ethylene oxide, or from tetrahydrofuran with starter compounds exhibiting hydrogen-activity, for example aliphatic alcohols, phenols, amines, carboxylic acids, water, or compounds based on natural substances, for example sucrose, sorbitol or mannitol, with use of a catalyst. Mention may be made here of basic catalysts and double-metal cyanide catalysts, as described by way of example in WO 2006/034800, EP 0090444, or WO 2005/090440.

According to step b) the comminuted polyurethane or polyisocyanurate provided in step a) Is depolymerized

Suitable processes for depolymerization are in principle known to the person skilled in the art. Preferably, the depolymerization is achieved by hydrolysis, (hydro-)alcoholysis, (hydro-)aminoly- sis or (hydro-)ammonolysis according to the present invention. Preferably, depolymerization is achieved by hydroglycolysis or hydrolysis according to the present invention. According to the present invention, the hydrolyzing step and the alcoholysing, ammonolysing or aminolysing step may be performed separately or may be combined. Typically, the amine corresponding to the isocyanate component used in the PU material is obtained by applying depolymerization processes comprising a hydrolysis step optionally together or after applying e.g. an alcoholysis, ammonolysis, or aminolysis.

Depending on the method used for depolymerization, different products are obtained. Preferably, it is possible to recover both starting material components from the polyurethane. Typically, the isocyanate component or an isocyanate precursor like an amine, carbamate or urea is obtained and can be separated but also the polyol component or monomer fragments of the polyol component is separated, Usually, the depolymerization results in a mixture of components which might be separated using suitable separation techniques. The process of the present invention thus may also comprise further separation steps.

According to a further embodiment, the present invention is directed to the process as disclosed above, wherein the depolymerization according to step b) is carried out by a method selected from hydrolysis, (hydro-)alcoholysis, (hydro-)aminolysis or (hydro-)ammonolysis.

After depolymerization, the process of the invention typically yields a polyamine comprising an amino group attached to the carbon atom to which in the initial polyisocyanate an isocyanate group was bound, e.g., methylene diphenyl diamines (MDA), oligomeric and polymeric methylene phenylene amine, toluenediamines (TDA), in particular 2,4 toluenediamine or 2,6-toluene- diamine, hexamethylene diamine (HDA), and naphthylene diamines (NDA). The polyesterpolyol (P1) or fragments thereof also can be re-isolated according to the present invention. The process typically yields polyol components comprising polyols or fragments of polyols, e.g., polyester polyols, fragments of polyester polyols. The components obtained in the depolymerization may be separated. It is also possible in the context of the present invention to separate by-products such as for example carbon dioxide, or waste materials prior to a separation of the amine component and the polyol components.

According to step c) of the process according to the present invention, the polyol components or polyol fragments and the amine component derived from depolymerization obtained in step b) are separated in an amine rich phase as mixture (MA) and an amine poor phase as mixture (MP).

Preferably, the process comprises allowing the mixture to settle. According to the present invention, it is possible that one or more phases are formed and the components of the mixture may be separated by suitable separation steps. According to the present invention, it is for example possible to extract the mixture via an organic anhydrous solvent which is not or partially miscible with water.

It can be beneficial if an excess of water is removed from the mixture, before allowing the mixture to settle, preferably by evaporation of the excess of water. In particular, for evaporation of the excess of water, the mixture is heated and/or a vacuum is applied. For example, an excess of water is removed by using flash evaporation or applying vacuum to the already heated mixture. For example, a water removal step may be performed for about 120 minutes or less, in particular about 90 minutes or less, for example about 75 minutes or less, for example about 60 minutes or less. Preferably, the water removal step is performed for about 10 minutes or more, in particular for about 30 minutes or more, for example for about 40 minutes or more.

Typically, mixture (MP) comprises polyesterpolyol (P1 ) or fragments thereof. The mixture may for example comprise polyalcohols and acids, in particular diacids. The amine poor phase may also comprise further components which may be separated from the remaining components.

The work-up of the depolymerization product, in particular the isolation of the polyamine and the polyol can be realized case dependent, for example by extractive work-up, precipitation of the amine component, for example as a hydrochloride, chromatography or distillation under reduced pressure. Preferably, the work up comprises several steps.

According to one aspect of the invention, solids may be removed from the mixture before or after the mixture is allowed to settle, preferably by one or more of the following: filtration, centrifugation, decantation.

It is for example possible to remove components such as for example solid components or flame retardants from the comminuted polyurethane or polyisocyanurate foam by suitable methods such as for example extraction. Other extractable components are other and sometimes even solid additives. The flame retardants may also be purified and reused. According to a further embodiment, the present invention is also directed to the process as disclosed above, wherein the process further comprises a step a1 ) a1) at least partial extraction of flame retardants from the the comminuted polyurethane or pol- yisocyanurate material.

Suitable conditions for step a1) are for example disclosed in EP 22205386.0.

According to a further embodiment, the present invention is also directed to the process as disclosed above, wherein the process further comprises a step c1) c1 ) removal of particulate solids from the reaction mixture.

Suitable methods for removal of particulate solids are in principle known to the person skilled in the art. For example, filtration units or a centrifuge may be used. Preferably, a filtration step is carried out according to the present invention using a filtration unit, more preferably a filter, more preferably a pocket filter, a bag filter, a membrane filter, a candle filter, an agitated pressure filter, a vacuum belt filter, a frame & plate filter, or a nutsche filter.

For filtration, preferably filter membranes having an average mesh size of about 30 pm or less may be used. It can be beneficial to use a cascade of filters. For example, a first filter membrane of the cascade of filters has an average mesh size of about 250 pm to about 290 pm. A second filter membrane of the cascade of filters preferably has an average mesh size of about 50 pm to about 90 pm and, in particular, a third filter membrane of the cascade of filters has an average mesh size of 20 pm or less.

In the alternative or additionally, centrifugation is a preferred solid-liquid-separation method.

Further separation steps may be carried out, for example separation steps to separate gaseous components such as for example carbon dioxide. Suitable separation methods are known to the person skilled in the art, such as for example evaporation or adsorption steps.

In work-up by distillation, compounds are separated according to their volatility, with more volatile compounds being separated first. Additives, water or solvents used in the depolymerization can also be removed via distillation prior further work-up of the polyol-polyamine mixtures. Generally, the “volatility” of a liquid may be described using its vapor pressure, wherein a high vapor pressure indicates a high volatility, and vice versa.

In the event that the polyamine is more volatile than the polyol as it is for example the case for TDA, monomeric MDA and NDA, the polyamine is recovered from the depolymerization product via distillation, preferably via distillation at reduced pressure. After distilling-off the polyamine, a distillation bottoms remains which contains the polyol.

Suitable conditions for the distillation are in principle known to the person skilled in the art and are for example disclosed in EP22178796.3 or EP22178797.1. Alternatively, the polyol component comprising polyetherpolyols, polyesterpolyols and/or fragments thereof may be recovered by extraction from the depolymerization mixture using a suitable extractant or a pair of extractants. It is also possible to precipitate the polyamine component in the form of it's hydrochloride by adding HCI and extracting the polyol component with a suitable solvent for example as described in DE2854940A1 , which is preferably dissolving the polyol component but not the hydrochlorides of the polyamine component. It is also possible to adjust the conditions in the extraction step to recover the polyamine component using aqueous HCI as extraction medium. The hydrochloride of the polyamine component can after separation then either be transferred to the free polyamine by adding a base but also directly used in the phos- genation to generate new polyisocyanates for the polyurethane synthesize. In case of MDA*HCI or PMDA*HCI the hydrochloride can be directly fed to an MDA synthesis plant at a position prior to the neutralization step.

Further, in particular for recovering the polyol substance, the process comprises preferably a work-up of the phase, which is polyol substance rich by purification of the polyol substance. According to the present invention it is possible to include purification steps for purifying the mixture (MP), the mixture (MP’) and/or the polyesterpolyols obtained. The purification may comprise one or more of the following:

- decantation;

- distillation;

- full or partial evaporation of the phase in one or more evaporators;

- contacting the phase with an ion exchange material;

- filtration;

- centrifugation;

- contacting the phase with one or more adsorbents.

- extraction using at least one solvent immiscible with the mixture MP or MP.’

Preferably, the process further comprises work-up of the mixture by purification of the amine substance, for example including distillation, in order to purify the amine substance.

It is understood that the separation process described above can be combined with any of the various embodiments of the inventive process described herein.

According to step d) of the process according to the present invention, the amine poor phase is treated to adjust the ratio of acids and polyalcohols in mixture (MP) to obtain mixture (MP’). Preferably, prior to step d), the water content in the mixture is adjusted, in particular reduced. The ratio of acids and polyalcohols is typically adjusted to obtain mixture (MP’) which is then suitable as a starting material for esterification of the acids and polyalcohols. Preferably, the ratio of acids is adjusted to a molar ratio of acid groups to hydroxy groups in the range of from 1 :1 .03 to 1 :2.5, in particular to 1 :1.05 to 1 :2.0. Typically, the amine poor phase comprises polyol components, such as polyols, for example glycerol and butandiol, and mono- or-diacids. Suitable treatment steps may for example comprise adding diacids to the mixture, adding polyalcohols to the mixture, addition of catalyst or removal of solvent from the mixture. Diacids may also be present in the form of diammonium salts. In case ammonium salts are present in the composition, the treatment according to step d) may comprise further treatments such as for example thermal treatments and/or vapor stripping to obtain the free acid prior to re-esterfication of the polyol fragments. The amine poor phase may also be treated to remove further by-products or solvents.

According to a further embodiment, the present invention is directed to the process as disclosed above, wherein the treatment according to step d) comprises one or more of the steps of adding diacids to the mixture; adding polyalcohols to the mixture; adding esterification catalysts, for example titan tetrabutanolate; removal of diols by evaporation /distillation; removal of solvent from the mixture.

The process of the present invention further comprises step e). According to step e) the mixture (MP’) is treated to achieve condensation of polyalcohols and acids in the mixture.

The treatment according to step e) is suitable to achieve re-condensation of polyols and acids. Suitable conditions for example for re-esterfication are known to the person skilled in the art and may for example include condensation of alcohols and acids by heating under vacuum and removal of condensation product, online analytics to follow reaction progress and optionally adjust monomer composition.

According to a further embodiment, the present invention is directed to the process as disclosed above, wherein the treatment according to step e) comprises heating under vacuum and removal of condensation product.

Furthermore, the process may comprise purification steps of the polyesterpolyol obtained. The purification may for example comprise contacting the polyesterpolyol with an ion exchange material; contacting the phase with one or more adsorbents, such as for example activated carbon or silicates, extraction, filtration and/or centrifugation. It is also possible to use the polyesterpolyol without further purification steps.

After work-up, the polyol-containing phase may be used at least proportionally in new PU formulations.

According to the present invention also the amine rich phase may be recovered. After purification, the polyamine preferably can be converted back to the corresponding isocyanate, for example by means of phosgenation, and as such can then be used at least proportionally as an isocyanate component in PU production. Alternatively, a reactive extraction of the polyamine with hydrogen chloride can be utilized as purification method according to the present invention. The formed polyamine-hydrochloride can be converted back to the corresponding isocyanate by means of direct phosgenation or can be transferred to an existing amine production plant. Suitable processes and reaction conditions are in principle known to the person skilled in the art.

The process according to the present invention comprises steps a), b), c), d) and e), but may also comprise further steps. The process may for example comprise further purification steps or heat treatments. According to a further embodiment, the present invention is also directed to the process as disclosed above, wherein the process comprises further purification steps.

Suitable treatment steps are in principle known to the person skilled in the art. Suitable treatment and/or purification steps may be carried out between steps a) and b), or between steps b) and c), or between steps c) and d) or between steps d) and e). In the context of the present invention it is also possible that step b) is carried out directly after step a). It is also possible that step c) is carried out directly after step b). Furthermore, it is possible that step d) is carried out directly after step c) and that step e) is carried out directly after step d).

According to the present invention, steps a) and b) might also be combined and carried out in the same apparatus. It is also possible that the composition provided in step a) might also comprise solvents, for example solvents which might be used in step b) of the process according to the present invention.

With the process of the present invention, about 90 % or more, preferably about 97 % or more, of the polyol substances which is theoretically recoverable from the polyurethane material can be released. Due to decomposition of monomers or incomplete recovery, the yield of the polyol substances is at least 30 wt.-%, preferably at least 40 wt.-%, in particular at least 45 wt.-%.

According to a further aspect, the present invention is also directed to a process for preparing a polyester polyol comprising the steps

(i) providing a mixture (MP) comprising acids and polyols which has been obtained by a depolymerization of at least one polyurethane or polyisocyanurate which is obtained from at least one polyesterpolyol (P1) ,

(ii) treatment of mixture (MP) to adjust the ratio of acids and polyalcohols in mixture (MP) to obtain mixture (MP’);

(iii) treatment of mixture (MP’) to achieve condensation of alcohols and acids in the mixture.

With respect to the steps of the process, reference is made to the disclosure above.

According to a further embodiment, the present inversion is also directed to a process for preparing a polyester polyol as disclosed above, wherein mixture (MP) is obtained by a process for recycling of polyurethane or polyisocyanurate containing waste comprising the steps of a) providing a composition (M1 ) comprising a comminuted polyurethane or polyisocy- anurate material which is obtained from at least one polyesterpolyol (P1) , b) depolymerization of the comminuted polyurethane or polyisocyanurate provided in step a); c) separation of the polyol components or polyol fragments from the amine component derived from foam cleavage obtained in step b), in an amine rich phase as mixture (MA) and an amine poor phase as mixture (MP).

According to the present invention, suitable additives, such as for example esterification catalysts, for example titan tetra butanolate may be added between steps (i) an (ii) of the process or between steps (ii) and (iii).

According to a further aspect, the present invention is also directed to the polyol composition obtained or obtainable according to the process as disclosed above. The polyesterpolyols obtained typically have an acid number of below 5, preferably of below 3, in particular of below 2. The OH number of the polyester polyols obtained may be in the range of from 25 to 800, in particular in the range of from 30 to 600, more preferable in the range of from 100 to 450. The viscosity [mPas@25°C] is typically in the range of from 100 to 30.000 mPas, preferably in the range of from 600 to 25000 mPas, more preferable in the range of from 1000 to 13000 mPas. The average molecular weight of the polyesterpolyols may be in the range of from 250 to 3000 g/mol, preferably in the range of from 300 to 2500 g/mol, in particular in the range of from 350 to 700 g/mol.

According to a further aspect, the present invention is also directed to the use of the polyol composition according to the present invention or a polyol composition obtained or obtainable according to the process of the present invention for the preparation of polyurethanes or polyisocyanurate containing polyurethan materials.

The present invention further relates to a process for preparing a polyurethane material by reacting the polyol substance obtained by the process according to the present invention with an isocyanate substance, preferably the isocyanate substance obtained by a process of the present invention.

According to a further embodiment, the present invention relates to the use of the polyol composition according to the present invention or a polyol composition obtained or obtainable according to the process as disclosed above for the preparation of polyurethanes or polyisocyanu- rates.

The present invention further relates to a process for preparing a polyurethane material by reacting the polyol substance obtained by the process according to the present invention with an isocyanate substance or by reacting a mixture comprising the polyol substance obtained by the process according to the present invention and one or more further polyols with an isocyanate substance.

The produced polyurethane material can in any suitable polyurethane application, preferably in the same application. The polyurethane material can for example be used in mattresses, furniture parts or car seats or in appliance or construction applications. The polyurethanes furthermore might be used in automotive parts, for example in dash boards, steering wheels, bumpers, in consumer goods like casual, sport or safety shoes; or for the preparation of thermoplastic polyurethanes.

According to the present invention, also the amine substance may be recovered. Thus, the invention also relates to a process for producing an isocyanate substance from an amine substance obtained by a process according to the present invention. The advantages and/or features described in connection with the process for recovering the polyesterpolyol also apply for the process for producing an isocyanate substance.

Preferably, the amine substance resulting from the recovery process is fed into a purification section of an amine producing plant, an amine storage tank or an isocyanate producing plant, for example in the phosgenation section of an isocyanate production plant.

Preferably the amine substance is phosgenated so that an isocyanate substance is formed. For example TDA may be phosgenated to prepare TDI, NDA may be phosgenated to prepare N DI, pMDA may be phosgenated to prepare pMDI, or MDA may be phosgenated to prepare MDI. Suitable conditions for the phosgenation are in principle known to the person skilled in the art.

In the context of the present invention, the term “isocyanate composition” encompasses all isocyanates known to the person skilled in the art in connection with polyurethane chemistry, such as, in particular, toluene diisocyanate (TDI; prepared from toluene diamine, TDA) or the di- and polyisocyanates of the diphenylmethane series (MDI; prepared from the di- and polyamines of the diphenylmethane series, MDA). The expression "isocyanate composition" also encompasses embodiments in which two or more different isocyanates (e.g. mixtures of MDI and TDI) have been used in the preparation of the polyurethane material. This also applies within one isocyanate class (that is to say, for example, also applies to various MDI types). Also further isocyanates such as hexamethylene diisocyanate (HDI) and its oligomers or naphthylene diisocyanate (NDI) may be present. The totality of all isocyanates used in the preparation of the polyurethane material is referred to as the isocyanate composition (of the polyurethane material). The isocyanate composition comprises at least one isocyanate.

According to a further embodiment, the present invention therefore is also directed to the process as disclosed above, wherein the process further comprises the conversion of the amine component to obtain an isocyanate composition. The conversion may for example be achieved by phosgenation or also by phosgene-free conversion. Suitable processes are for example liquid phosgenation, gasphase phosgenation or gas-liquid phosgenation or a phosgenation via salt or a phosgene-free conversion for example carbamate cleavage. Suitable conditions for the phosgenation are in principle known to the person skilled in the art and are for example disclosed in Ullmann’s Encyclopedia of Industrial Chemistry, 7^th ed. Vol. 20, 2012, p. 63-82, WO 99/54289 A, WO 2004/056756 A (liquid phosgenation); Ullmann’s Encyclopedia of Industrial Chemistry, 4^th ed. Vol. 13, 2012, p. 353, DE 25 870847 A, EP 1532107 A, EP 0570799 A EP 0289840 A (gasphase phosgenation); or EP 2044009 A1 , WO 2013/060836 A, WO 2013/079517 A (gas-liquid phosgenation). An example of gas-liquid phosgenation process is disclosed in WO 2022/106716, examples of gas phase phosgenation processes are disclosed in EP 1761483 B1 , EP 2079684 B1 , EP 2188247 B1 , EP 2408738 B1 and EP 2539314 B1 and examples of phosgene-free conversion are disclosed in WO2018/185168 and EP 3250 622 B1 .

Preferably, the phosgenation comprises admixing a solvent to the amine component and stirring, more preferably at a temperature in the range of from 50 to 180 °C, more preferably in the range of from 70 to 140 °C, more preferably in the range of from 80 to 120 °C, obtaining a polyamine mixture; and bringing the polyamine mixture in contact with phosgene in a reactor and heating the obtained mixture to a temperature in the range of from 90 to 140 °C, more preferably in the range of from 110 to 130 °C, obtaining a mixture comprising one or more polyisocyanates.

Further embodiments of the present invention can be found in the claims and the examples. It will be appreciated that the features of the subject matter/processes/uses according to the invention that are mentioned above and elucidated below are usable not only in the combination specified in each case but also in other combinations without departing from the scope of the invention. For example, the combination of a preferred feature with a particularly preferred feature or of a feature not characterized further with a particularly preferred feature etc. is thus also encompassed implicitly even if this combination is not mentioned explicitly.

Illustrative embodiments of the present invention are listed below, but these do not restrict the present invention. In particular, the present invention also encompasses those embodiments which result from the dependency references and hence combinations specified hereinafter.

1 . A process for recycling of polyurethane or polyisocyanurate containing waste comprising the steps of a) providing a composition (M1) comprising a comminuted polyurethane or polyisocyanurate material which is obtained from at least one polyesterpolyol (P1) , b) depolymerization of the comminuted polyurethane or polyisocyanurate provided in step a); c) separation of the polyol components or polyol fragments from the amine component derived from foam cleavage obtained in step b), in an amine rich phase as mixture (MA) and an amine poor phase as mixture (MP); d) treatment of the amine poor phase to adjust the ratio of acids and polyalcohols in mixture (MP) to obtain mixture (MP’); e) treatment of mixture (MP’) to achieve condensation of polyalcohols and acids in the mixture. The process according to embodiment 1 , wherein the treatment according to step d) comprises one or more of the steps of adding diacids to the mixture; adding polyalcohols to the mixture; removal of solvent from the mixture. The process according to embodiment 1 or 2, wherein the depolymerization according to step b) is carried out by a method selected from hydrolysis, (hydro-)alcoholysis, (hydro- )aminolysis or (hydro-)ammonolysis. The process according to any of embodiments 1 to 3, wherein the treatment according to step e) comprises heating under vacuum and removal of condensation product. The process according to any one of embodiments 1 to 4, wherein the process further comprises a step c1) c1 ) removal of particulate solids from the reaction mixture. The process according to any one of embodiments 1 to 5, wherein the process comprises further purification steps. Process for preparing a polyester polyol comprising the steps

(iii) treatment of mixture (M P’) to achieve condensation of alcohols and acids in the mixture. 8. The process according to embodiment 7, wherein the treatment according to step (ii) comprises one or more of the steps of adding diacids to the mixture; adding polyalcohols to the mixture; removal of solvent from the mixture.

9. The process according to embodiment 7 or 8, wherein the depolymerization according to step (i) is carried out by a method selected from hydrolysis, (hydro-)alcoholysis, (hydro- )aminolysis or (hydro-)ammonolysis.

10. The process according to any of embodiments 7 to 9, wherein the treatment according to step (iii) comprises heating under vacuum and removal of condensation product.

11 . The process according to any one of embodiments 7 to 10, wherein the process comprises further purification steps.

12. Polyol composition obtained or obtainable according to the process according to any one of embodiments 1 to 11.

13. Polyol composition obtained or obtainable according to the process for recycling of polyurethane or polyisocyanurate containing waste comprising the steps of a) providing a composition (M1) comprising a comminuted polyurethane or polyisocyanurate material which is obtained from at least one polyesterpolyol (P1) , b) depolymerization of the comminuted polyurethane or polyisocyanurate provided in step a); c) separation of the polyol components or polyol fragments from the amine component derived from foam cleavage obtained in step b), in an amine rich phase as mixture (MA) and an amine poor phase as mixture (MP); d) treatment of the amine poor phase to adjust the ratio of acids and polyalcohols in mixture (MP) to obtain mixture (MP’); e) treatment of mixture (MP’) to achieve condensation of polyalcohols and acids in the mixture.

14. Polyol composition obtained or obtainable according to the process for preparing a polyester polyol comprising the steps (i) providing a mixture (MP) comprising acids and polyols which has been obtained by a depolymerization of at least one polyurethane or polyisocyanurate which is obtained from at least one polyesterpolyol (P1),

15. Use of the polyol composition according to embodiment 12 to 14 or a polyol composition obtained or obtainable according to the process of any one of embodiments 1 to 11 for the preparation of polyurethanes or polyisocyanurates.

16. A process for recycling of polyurethane or polyisocyanurate containing waste comprising the steps of a) providing a composition (M1) comprising a comminuted polyurethane or polyisocyanurate foam which is obtained from at least one polyesterpolyol (P1) , b) depolymerization of the comminuted polyurethane or polyisocyanurate provided in step a); c) separation of the polyol components or polyol fragments from the amine component derived from foam cleavage obtained in step b), in an amine rich phase as mixture (MA) and an amine poor phase as mixture (MP); d) treatment of the amine poor phase to adjust the ratio of acids and polyalcohols in mixture (MP) to obtain mixture (MP’); e) treatment of mixture (MP’) to achieve condensation of polyalcohols and acids in the mixture.

17. The process according to embodiment 16, wherein the treatment according to step d) comprises one or more of the steps of adding diacids to the mixture; adding polyalcohols to the mixture; removal of solvent from the mixture.

18. The process according to embodiment 16 or 17, wherein the depolymerization according to step b) is carried out by a method selected from hydrolysis, (hydro-)alcoholysis, (hydro- )aminolysis or (hydro-)ammonolysis. The process according to any of embodiments 16 to 18, wherein the treatment according to step e) comprises heating under vacuum and removal of condensation product. The process according to any one of embodiments 16 to 19, wherein the process further comprises a step c1) c1 ) removal of particulate solids from the reaction mixture. The process according to any one of embodiments 16 to 20, wherein the process comprises further purification steps. Process for preparing a polyester polyol comprising the steps

(iii) treatment of mixture (MP’) to achieve condensation of alcohols and acids in the mixture. The process according to embodiment 22, wherein the treatment according to step (ii) comprises one or more of the steps of adding diacids to the mixture; adding polyalcohols to the mixture; removal of solvent from the mixture. The process according to embodiment 22 or 23, wherein the depolymerization according to step (i) is carried out by a method selected from hydrolysis, (hydro-)alcoholysis, (hydro- )aminolysis or (hydro-)ammonolysis. The process according to any of embodiments 22 to 24, wherein the treatment according to step (iii) comprises heating under vacuum and removal of condensation product. The process according to any one of embodiments 22 to 25, wherein the process comprises further purification steps. Polyol composition obtained or obtainable according to the process according to any one of embodiments 16 to 26. Polyol composition obtained or obtainable according to the process for recycling of polyurethane or polyisocyanurate containing waste comprising the steps of a) providing a composition (M1) comprising a comminuted polyurethane or polyisocy- anurate foam which is obtained from at least one polyesterpolyol (P1) , b) depolymerization of the comminuted polyurethane or polyisocyanurate provided in step a); c) separation of the polyol components or polyol fragments from the amine component derived from foam cleavage obtained in step b), in an amine rich phase as mixture (MA) and an amine poor phase as mixture (MP); d) treatment of the amine poor phase to adjust the ratio of acids and polyalcohols in mixture (MP) to obtain mixture (MP’); e) treatment of mixture (MP’) to achieve condensation of polyalcohols and acids in the mixture.

29. Polyol composition obtained or obtainable according to the process for preparing a polyester polyol comprising the steps

(i) providing a mixture (MP) comprising acids and polyols which has been obtained by a depolymerization of at least one polyurethane or polyisocyanurate which is obtained from at least one polyesterpolyol (P1),

30. Use of the polyol composition according to embodiment 27 to 28 or a polyol composition obtained or obtainable according to the process of any one of embodiments 16 to 26 for the preparation of polyurethanes or polyisocyanurates.

Literature cited:

WO 2022/171586

US 2022/0251328

US 9,023,907 B2

WO 2015/121057

WO 2013/139781 "Kunststoffhandbuch [Plastics handbook], volume 7, Polyurethane [Polyurethanes]", Carl Hanser Verlag, 3rd edition 1993, chapter 3.1 , 3.2 and 3.3.2

WO 2006/034800

EP 0090444

WO 2005/090440

EP22178796.3

EP22178797.1

DE2854940A1

Ullmann’s Encyclopedia of Industrial Chemistry, 7^th ed. Vol. 20, 2012, p. 63-82

WO 99/54289 A

WO 2004/056756 A

Ullmann’s Encyclopedia of Industrial Chemistry, 4^th ed. Vol. 13, 2012, p. 353

DE 25 870847 A

EP 1532107 A

EP 0570799 A

EP 0289840 A

EP 2044009 A1

WO 2013/060836 A

WO 2013/079517 A

WO 2022/106716

EP 1761483 B1

EP 2079684 B1

EP 2188247 B1

EP 2408738 B1

EP 2539314 B1

WO2018/185168

EP 3 250 622 B1

Claims

1 . A process for recycling of polyurethane or polyisocyanurate containing waste comprising the steps of a) providing a composition (M1) comprising a comminuted polyurethane or polyisocyanurate material which is obtained from at least one polyesterpolyol (P1), b) depolymerization of the comminuted polyurethane or polyisocyanurate provided in step a); c) separation of the polyol components or polyol fragments from the amine component derived from foam cleavage obtained in step b), in an amine rich phase as mixture (MA) and an amine poor phase as mixture (MP); d) treatment of the amine poor phase to adjust the ratio of acids and polyalcohols in mixture (MP) to obtain mixture (MP’); e) treatment of mixture (MP’) to achieve condensation of polyalcohols and acids in the mixture.

2. The process according to claim 1 , wherein the treatment according to step d) comprises one or more of the steps of adding diacids to the mixture; adding polyalcohols to the mixture; removal of solvent from the mixture.

3. The process according to claim 1 or 2, wherein the depolymerization according to step b) is carried out by a method selected from hydrolysis, (hydro-)alcoholysis, (hydro-)aminoly- sis or (hydro-)ammonolysis.

4. The process according to any of claims 1 to 3, wherein the treatment according to step e) comprises heating under vacuum and removal of condensation product.

5. The process according to any one of claims 1 to 4, wherein the process further comprises a step c1) c1 ) removal of particulate solids from the reaction mixture.

6. The process according to any one of claims 1 to 5, wherein the process comprises further purification steps.

7. Process for preparing a polyester polyol comprising the steps (i) providing a mixture (MP) comprising acids and polyols which has been obtained by a depolymerization of at least one polyurethane or polyisocyanurate which is obtained from at least one polyesterpolyol (P1) ,

8. The process according to claim 7, wherein mixture (MP) is obtained by a process for recycling of polyurethane or polyisocyanurate containing waste comprising the steps of a) providing a composition (M1) comprising a comminuted polyurethane or polyisocyanurate material which is obtained from at least one polyesterpolyol (P1) , b) depolymerization of the comminuted polyurethane or polyisocyanurate provided in step a); c) separation of the polyol components or polyol fragments from the amine component derived from foam cleavage obtained in step b), in an amine rich phase as mixture (MA) and an amine poor phase as mixture (MP).

9. Polyol composition obtained or obtainable according to the process according to any one of claims 1 to 8.

10. Use of the polyol composition according to claim 9 or a polyol composition obtained or obtainable according to the process of any one of claims 1 to 8 for the preparation of polyurethanes or polyisocyanurates.